Madeleine McCann is still alive and was snatched by someone who wanted a child to love, claims the ex-policeman hunting her.

David Edgar today reveals why he is convinced the youngster is not dead – while dismissing all other theories so far put forward about her disappearance.

The 52-year-old dad-of-two believes Madeleine was simply “in the wrong place at the wrong time” when she was kidnapped from her holiday flat at Praia da Luz on May 2007, aged three.

Mr Edgar spoke as her parents Kate and Gerry prepared to sue disgraced former Portuguese police chief Goncalo Amaral over “offensive” claims they were involved in her disappearance.

He said: “Everybody hopes she has been taken by someone who wanted a child to take care of. That’s also my theory because it is supported by obvious facts.”

He said other claims about what happened do not stand up.

- Taken by child traffickers: Former RUC and Cheshire officer Mr Edgar, who has more than 30 years’ experience investigating murders, kidnappings and sex crimes, said: “There has been a huge reward offered. One of the gang would have broken ranks by now and come forward for the money.”

- Abducted by paedophile: “Most child-abusers dump the body quicklyand near the scene with little or no attempt to hide it. It’s a statistical fact. No trace of Madeleine, or her clothing, was found in a search.”

- Wandered off and fell down a hole:“The Portuguese searched the drainage tunnels. Again, no body.”

- Stumbled into the clutches of a paedophile: “A three-year-old is out in the street and comes across an abductor who happens to be walking by? It doesn’t happen. Most people seeing a child out in nightclothes take them to look for the parents.”

- Parents killed her and dumped the body: “Not the slightest shred of evidence.”

Mr Edgar added: “There are good grounds for believing Madeleine is alive. I can justify it by the evidence.”

Kate and Gerry will take legal action against Amaral over his comments in a book he wrote.

The couple, of Rothley, Leics, said: “These are unfounded and grossly defamatory claims.”

Kate and Gerry are today due to mark International Missing Children’s Day in London by joining other families who have lost youngsters.